In photography the regulations relating to the disposal of spent water have become more restrictive. It has been suggested to treat the rinsing water so as to be able to recycle it inside the machine in order to reduce the water flows and trap the silver freed during processing. To adapt the operation of machines manufactured prior to the introduction of the new rules and to make them compatible with these new regulations, an independent filtering device has been suggested that connects to the processing installation. In particular this device comprises a treatment tank equipped with a pump enabling spent water to be taken from the rinsing tank and then after treatment to be sent back to the rinsing tank. This device is arranged outside the processing machine.
In the embodiment of the invention that is intended to be utilized on machines for developing X-ray plates the rinsing water contains silver ions and gelatin particles. The recycling device that is used comprises a first type of filter to trap the silver ions in order to limit the concentration to a value less than the regulatory threshold and a second type of filter enabling the gradual release of a biocide so as to inhibit the growth and/or proliferation of microorganisms. To efficiently treat the rinsing waters, the flow rate of the pump is adapted to the volume of the rinsing tank to make the whole volume contained in the tank circulate every few minutes.
For various reasons, especially the processing machine maintenance, the design of certain machines currently on the market or the arrangement of the filtering device in relation to the machine, unpriming of the pump may occur. This phenomenon causes the normal operation of the filtering device to stop, which in turn causes poor functioning of the processing machine.
The invention aims to avoid this disadvantage.